Method of producing absorbent and resilient felt



Feb. 13, 1934. PLUVMSTEAD 1,947,108

METHOD OF PRODUCING ABSORBENT AND RESILIENT FELT Original Filed Sept. 5, 1931 xnRsbuE A WATER Ba E C 7 v AIR m SOLUTION OR SOLUTION :fi

F EAN 0R PUP 13 CENT/Pl FUGE r M1 JYl JH M1 I J WEA K STRONG 2) P/Pooucr SOLUTION SOLUTION Invgnior:

FOR REClA/M/NG tl ie h EBZ;

a /M wm AW- Patented Feb. 13, 1934 'Joseph E. Plumstead, w

n, M, assignor ilmmgto to The Jessup & Moore Paper 00., Philadelphia, Pa a corporation of Massachusetts Application September 5, 1931, Serial No. 561,479 Renewed January 8, 1934 The invention relates to a method of producing kinked, curled, twisted, or crimped fibres from finished or prepared cellulosic fibrous pulp material for the production ofa sheet of material or 6 felted product having a high degree of bulk and absorbency.

An -object of the invention is the production of curled or krinkled fibres from' finished or prepared pulp without the necessity of using as drasld tic treating solutions as have heretofore been used to produce the desired degree of bulkiness in the felted fibrous sheet.

Or expressed in another way, this object is to provide a method capable of producing a felted product having an increased degree of bulkiness or absorbency, using the usual or ordinary treating solution, or treating solutions of less or equivalent drasticity. In other words, for a treating solution of given drasticity, the method of the present invention produces increased bulk and absorbency in the resultant sheet over that produced by methods used heretofore.

Another object is to produce the less drastic treating solutions by using less drastic chemicals 96 or by using a less concentrated solution of the same or an equally drastic chemical as that used in the usual or ordinary treating solution, or by using combinations of two or more chemicals.

Another object is to producea flushing of the treating solution through the pulp mass without substantial dilution to produce the curling action, and to effectively remove the treating solution from the pulp mass in substantially one mechanical action.

A further object is to produce a centrifugal flushing of treating solution through the fibres subjected to centrifugal action in a batch or a continuous centrifuge, and also any wash water, to perform the'operation of fibre curling, chemical removal, and fibre washing substantially in one mechanical step, when desired, while providing for intermediate drying of the fibres withv the treating solution thereon, prior to the washing operation, when desired.

Another object is to provide for a further drying of the fibres subsequent to the washing operation.

Another object is to secure a concentration of the residual treating solution on the fibres by evaporation and a consequent accelerated or accentuated curling eifect even with fibre curling solutions of reduced drasticity, i. e., below mercerizing strength.

Another object is to provide for thorough fiushing of the fibres with treating solution sufliciently to cause curling thereof without mechanical pressure and without substantial agitation of the fibres one upon another.

Other objects will appear hereinafter.

The invention consists in the method of procedure and treatment of finished or prepared pulp fibres for producing curled fibres and a highly absorbent felted product, as hereinafter described and particularly pointed out in the claims.

The drawing is diagrammatically illustrative 65 of certain features of the invention.

The drawing diagrammatically illustrates one arrangement suitable for performing my invention including treatment in a cetrifuge.

The invention involves treatingfinished or pre- W pared cellulosic fibres with a curling agent or treating solution and supplementing or accelerating the fibre curling effect of the treating solution or curling agent by drying the fibres with treating solution thereon. V5

The curling effect is substantially increased by reason of drying the fibres with the solution thereon, and enables the use of a less drastic or less powerful curling agent or treating solution in producing a felted product ofa desired or given 99 degree of bulk and absorbency. The less drastic fibre curling agent is less powerful than usual or ordinary caustic lye treating solution, whether because of increased percentage of diluting solvent or because of the use of a less active or more 35 inert chemical.

The process may include the steps of treating the finished or prepared fibres with the treating solution or curling agent which may be of reduced power, and after treatment is effected thoroughly by agitation or kneading or otherwise impregnating, as by centrifugal action, the preponderance of the curling agent is expressed or expelled, and the fibres are then dried with the residual treating solution thereon, and without washing.

After the fibres are dried and curled with the curling agent thereon, they may be washed to remove the curling agent, and subsequently formed into a felted product of a high degree of 100 bulk and absorbency.

The invention also contemplates again drying the washed fibres prior to the felting operation. I have found that if fibrous cellulose material is saturated and worked or kneaded or otherwise impregnated as by centrifugal action, with a 5% caustic soda solution or with a 6% of sodium sulfide solution, or with 2% caustic soda solution, mixed with -'7% CuO on the weight of the fibre and if after impregnation of the fibres with any 1 5% solution expressed and mass dried without washing is equivalent in resultant product to 15% solution expressed and not dried before washing. Expressed dryness 40% pulp and 60% solution in each case.

15% solution 5% solution 60 parts 15% solution, equivalent 9 to 9 pigts lggZ; chemical parts 0 em! 40 parts mm) 22.5% chemical 60 parts 5% solution, equivalent to 3 parts 100% chemical 3 parts chemical 1 ca140 parts pulp 75% chem! Preferably, the method of curling, including the drying of the curling agent on the fibres, is performed by treating the finished or prepared cellulosic pulp fibres with a fibre curling agent, which may be of reduced power or drasticity, in or on an. agitating, working or kneading or other treating or impregnating vessel or device, such as a centrifuge, then expressing or expelling the preponderance of the fibre curling agent from the fibres in the vessel, then drying the fibres with the curling agent thereon,, as by introducing warm air into and through the mass of fibres in the treating device, washing the dried and curled fibres, and subsequently discharging the curled fibres from said treating device. If desired, the washed fibres may be dried again before discharge from the treating device. According to my invention, the entire procedure is performed within or on the vessel or device as a substantially continuous or single performance.

The invention particularly contemplates including the action of a centrifuge in the method of treatment including impregnating the finished fibres with the curling agent by the centrifugal action in the centrifuge, expelling the curling agent by the same action, then drying the fibres with the treating solution thereon preferably with the assistance of the whirling action of the centrifuge preferably supplemented by the introduction of a current of warm dry air into the centrifuee.

The invention also involves the method of curling of cellulose fibres including mechanical treatment in a centrifuge, consisting in placing the fibres either shredded or unshredded, and either mixed or unmixed with treating chemical solution, in either a batch or continuous centrifuge and flushing through the fibres, the treating solution and also any wash water, thereby performing the operations of fibre curling, chemical solution removal, and fibre washing, substantially in one mechanical step or operation.

Preferably the pulp is first shredded and then conveyed by means of air, water, or treating solution, to a rapidly revolving perforated basket of a centrifuge, onthe perforated walls of which basket, the layer of fibres is built up. This layer is held to the perforated wall by centrifugal force. Treating solution, which may be associated with the fibres or showered upon the fibres will be rapidly flushed through the fibre wall and through the perforated walls of the revolving basket by centrifugal force, thereby causing a thorough memos flushing of the treating solution in contact with the fibres and its removal from the rapidly revolving wall of fibrous material. Washing may be done in stages or continuously as indicated in the drawing.

' Referring to this figure, which is purely diagrammatic, A represents the shredder which may include solution showers A-1, with conduit A--2 communicating with the centrifuge B, the pulp conveying air or solution being supplied from source 0 by means of fan or pump D into the conduit A2. The centrifuge B comprises an outer stationary bowl or basket B-1, and the perforated revolving basket B-2 within the outer bowl 3-1 and driven by a suitable motor B-3. A source of treating solution or fibre curling agent is indicated diagrammatically at E with a suitable valve E-l delivering treating solution to conduit F and to the centrifuge. A valved water supply N is also in communication with the conduit F. At G is shown the discharge for the curled fibre product, strong solution being Withdrawn as diagrammatically indicated at H and returned to the source of treating solution supply at E by means of conduit K. Weak solution for reclaiming is drawn off at L as shown at a dificrent stage of the operation of the centrifuge shown which is diagrammatically representative of a batch centrifuge. My method might be performed in a continuous type of centrifuge, as is apparent.

The solution showers are employed when a wet mix is supplied to the centrifuge, while when dry fibres are conveyed to the centrifuge by air, as from C, the solution showers at A-1 may not be used, except for dust dampening.

If a continuous centrifuge is used internal troughs must be provided on the interior of the stationary basket to collect and classify the vary ing strengths of solution. These troughs are diagrammatically represented in the drawing at M-1, M-1 representing the vanes which may serve to deflect the air or treating solution, the latter in the case of the continuous centrifuge.

With a batch centrifuge the solution or wash water discharge would be expelled in stages and the classification of efluent solution would be effected by valves in pipe lines to tanks H and L.

,Any of the well brown types of batch or con tinuous centrifuges may be used in performing my method, except that in the case of air fioating and air disposal of the shredded material on the perforated walls of the centrifuge inner revolving basket, I provide the exterior of the walls of the inner rotary centrifuge bowl with vanes as shown at M which will cause a current of air to be pulled through the perforated walls of the centrifuge bowl in order to deposit an even layer of the fibrous material thereon. The in= terior of the outer stationary basket may also be provided with cooperating vanes lVi-l, if desired, the lower vanes M'l serving to guide the solution into the valved solution withdrawal conduits L and H.

The method of curling fibres with centrifugal action in the centrifuge causes a thorough flushing of the fibres with treating solution, sumciently to cause curling thereof without mechanical pressure and without the agitation of the fibres one upon another. the fibres to lie in a dormant state as far as the relation to one another is concerned, while the treating solution is rapidly flushed past eachfibre and through the fibre mat. This method is particularly valuable for producing a high I This method causes ace-moa degree of freenessand bulk and flufliness or felted product aswell as absorbency.

ll am fully aware that various chemicals in solution, including 'sodium'sulfide and caustic soda have been used for-many years for the purpose of reacting with the acid cementitious intercellular materials which nature has provided to substances but the purpose of this invention is operations.

.to take cellulose fibres which have been previously separated and cleansed by anyof the well-known chemical processes and to treat these fibres as herein described for the ..purpose of presenting a product different from that produced by any of the usual'pulp producing processes namely, the soda process, the sulfite process, the mono-sulfite process or the sulfate or Kraft process. These are the well known processes for producing ordinary pulp from vegetable raw material.

A solution of caustic'lye (of about 1% to 16% concentration) which is less powerful or less drastic than the usual causticlyetreating solutions (of about 7% to 24% concentration), may be used and will produce the desired effect when dried on the fibre after expressing or expelling the preponderance thereof.

The product of the present invention is a 11-- brous mass of extreme freeness'requiring a modified Schopper tester. For a more full description of the product, reference is made to my copending application, Ser. No. 558,826, filed August 22, 1931, for Method of producing absorbent or resilient felt,.or to my copending application Ser. No. 561,242, filed September 4, 1931 for Method of producing absorbent or resilient felt.

It is not intended to limit the invention to the specific illustrations given in the specification by way of example.

It will be understood that where expressing ofthe treating solution from the fibres is referred to in the specification andclaimsQthe word expressing is used to refer to expelling treating solution mechanical action as distinguished is applied to the fibres or the expressing is accomplished by centrifugal forcev as herein disclosed without mechanical pressure.

The discovery which I have made, in addition 2 to the use of the centrifugal machine for the curling of fibres, resides in the fact that as residual treating solution is concentrated when clinging drastic or more concentrated treating solution.

It would also be possible to form the solution saturated fibresinto a sheet and dry the sheet and solution continuously in the same manner in which paper is usually dried, thereafter breaking down the sheet again into pulp form, washer ing out the treating chemical, and reforming again into a felted product.

lit is apparent that these alternative methods do not have the advantage of one mechanical operation without disturbing the relative location of one fibre to another as is the case in centrifuge irrespective of whether mechan-' While finished of prep pulp is herein referred to as being treated with fibre curling agent it will be apparent that in the pulp making'or preparing process after the cooking operation the fibres are saturated with spent coofing-solution. This solution may be dried on the fibres and result in curling eiicct. In this case the fibre curling agent with which the finished or prepared pulp is treated comprises the spent cooking solution which remains in the prepared pulp.

l. The hereindescribed process of curling fibres for making absorbing paper comprising introducing finished or prepared cellulosic paper felting fibrous material into a centrifuge, building up a layer of said fibres in pulp form on the wall of tion, by centrifugal force thereby building up a layerof said felting fibres in pulp form and simultaneously flushing said fibres as they are built up into said layer with the caustic soda solution, and continuing the centrifugal action to dry the built-up layer of fibres with some of the caustic soda remaining thereon, said fibres during the centrifugal action being free from restraint tending to retard or prevent their curling.

3. The process according to claim 2 in which the caustic soda solution is of non-merce strength.

4. The process according to c 2 in which the caustic soda solution is of non-memorizing strength and the drying action is performed with a current of warm air. v

I 5. The hereindescribed process of curling fibres up a layer of said fibres in pulp form on thewall' of said centrifuge by the centrifugal action thereof, and flushing caustic soda solution of non-- mercerizing strength through the fibres by said centrifugal action said fibres during the centrifugal action being free from restraint tending to retard or prevent their curling.

6. A method according to claim 5 in which the fluid is in the form of a liquid.

'3. A process according to claim 1 in which the centrifugal action is carried on in the presence of a current of warm air passing through the layer of fibres.

8. The hereindescribed process of curling fibres for making absorbent paper comprising subjecting finished or prepared cellulosic paper-felting fibres to the curling action of caustic soda under centrifugal force in a centrifuge to cause the individual fibres to be flushed and curled by said caustic soda, and continuing the centrifugal action for drying the fibres with some of the caustic soda concentrated thereon, said fibres being free from restraint tending to retard or prevent their curling.

JOSEPH E. PLUMS'IEAD. 

